Project Summary/Abstract The World Health Organization (WHO) estimates that ambient air pollution was responsible for over 7 million premature deaths worldwide in 2014. Of various forms of air pollution, fine particulate matter (particles with aerodynamic diameter ? 2.5m; PM2.5) pollution has become one of the world?s leading environmental problems. China, a country to some of the most polluted cities in the world, is undergoing rapid transitions with respect to demographics, air pollution, and climate change, with substantial implications for human health. The Global Burden of Diseases, Injuries, and Risk Factors Study 2015 (GBD 2015) estimated that 1.1 million premature deaths and 22 million disability-adjusted life years (DALYs) were attributable to ambient PM2.5 exposure in China in 2015. Existing research have also shown that rising Asian emissions increases air pollution in North America, extending the scope of the problem and especially its relevance to the United States. The short-term (i.e. daily) and long-term (i.e. annual) effects of PM2.5 on mortality have been well characterized in existing research, but intermediate-term (i.e. monthly) effects of PM2.5 on mortality have not yet been studied. In addition, the effects of climate change on PM2.5 levels in the future are uncertain. The proposed study aims to fill these important gaps in research from both original epidemiologic and modeling work. First, using air quality and mortality data from the Chinese Center for Disease Control and Prevention (China CDC), we will investigate the association between monthly exposure to PM2.5 and non-accidental mortality using data from 43 counties in China from 2013 to 2015. Second, using the Geophysical Fluid Dynamics Laboratory Coupled Physical Model 3 (GFDL CM3), a global climate model developed by the National Oceanic and Atmospheric Administration (NOAA), we will hold emissions fixed at 2005 levels and estimate the excess number of deaths in 2050 due to climate change-driven changes in PM2.5 concentrations in China and the U.S. Third, using the same model, we will allow emissions to vary based on plausible future pollution emission scenarios, and compute the excess number of deaths in China and the U.S. resulting from emission policies in China. Over the next two to three years, China will begin developing its next five-year plan, including targets for both air pollution and greenhouse gas emissions. Given this timing, the work we propose here has the potential to play an important role in this planning process. The policy influence of our outputs and outcomes of this project will be strengthened by our ongoing working relationship with key Chinese partners, all of whom play a role in current air quality and/or environmental health planning in China. We are uniquely positioned to provide a very large impact on the course of China?s air pollution mitigation policies. Furthermore, as mentioned earlier, changes in Chinese emissions could impact air pollutant concentrations in the U.S. Our work is especially designed to quantify such effects, and our proposed integration of future global emission scenarios aligned with their latest policy plans for greenhouse gases and air pollutants is a major advance towards providing more useful science for informing regional and global policies.